Merge branch 'master' of github.com:leancloud/javascript-sdk into feature/2015.07.09

Author: killme2008

lib/utils.js

@@ -97,7 +97,7 @@
   };
 
   // Set the server for AV to talk to.
-  AV.serverURL = "https://cn.avoscloud.com";
+  AV.serverURL = "https://api.leancloud.cn";
 
   // Check whether we are running in Node.js.
   if (typeof(process) !== "undefined" &&
@@ -128,6 +128,9 @@
    * @param {String} applicationKey Your AV Application Key
    */
    AV._initialize = function(applicationId, applicationKey, masterKey) {
+    if (AV.applicationId !== undefined) {
+      console.warn('AVOSCloud SDK is already initialized, please don\'t reinitialize it.');
+    }
     AV.applicationId = applicationId;
     AV.applicationKey = applicationKey;
     AV.masterKey = masterKey;